1. Field of the Invention
The present invention relates to mobile communication service, and more particularly to a method of paging a hybrid access terminal supporting both voice service and high-speed packet data service.
2. Description of the Related Art
In general, wireless communication systems performing 3rd generation wireless communication include, for example, Code Division Multiple Access (CDMA) 2000 1x, Wideband Code Division Multiple Access/Universal Mobile Telecommunications System (WCDMA/UMTS), General Packet Radio System (GPRS) and CDMA 2000 Evolution in Data Only (1xEV-DO).
As the system standard is currently being changed from IS-2000 which corresponds to a CDMA 2000 1x standard capable of simultaneously supporting voice service and packet data service to IS-856 which corresponds to a CDMA 2000 1xEV-DO standard supporting only high-speed packet data service, a hybrid access terminal (HAT) capable of having access to the two systems has been developed. The hybrid access terminal is designed to simultaneously monitor both the CDMA 2000 1xEV-DO system and the CDMA 2000 1x system, but automatically shifts to a state in which it monitors only the CDMA 2000 1x system if an idle state of the CDMA 2000 1xEV-DO system lasts for a predetermined period of time in order to further reduce battery consumption.
A system capable of transmitting large capacity data such as the CDMA 2000 1xEV-DO system provides a multimedia message service (MMS) which is an improvement over the existing short message service (SMS) to satisfy the additional variety of customer demands. The multimedia message service is a service which enables not only characters, but also multimedia data including graphics or photograph, music and video clips to be given and taken via a mobile terminal. By virtue of the improvement in speed in wireless communication, the launch of color terminals capable of reproducing moving pictures, etc., it is expected that the multimedia message service hereafter occupies the heart of the 3rd generation mobile communication service. Therefore, the major mobile communication service providers also show a great interest in constructing the multimedia message service and are preparing a variety of supplementary services applying the multimedia message service, such as photographs, messages, moving picture cards, moving advertisements, etc.
Similarly for the short message service, a multimedia message service is provided by using an overhead channel, not a traffic channel such as a control channel or a paging channel. A mobile terminal periodically or continuously monitors additional channels in an idle state so as to obtain a short message or a multimedia message and to respond to a paging from a system.
However, as described above, if a predetermined period of time elapse after an idle state of the CDMA 2000 1xEV-DO system starts, the hybrid access terminal automatically shifts to a state in which it monitors only the CDMA 2000 1x system while simultaneously monitoring both the CDMA 2000 1xEV-DO system and the CDMA 2000 1x system. Accordingly, the hybrid access terminal has a problem in that it cannot continuously monitor the CDMA 2000 1xEV-DO system, and thus cannot use a multimedia message service through the CDMA 2000 1xEV-DO system.